1. Field of the Invention
The present invention concerns a control and/or indicator unit with screw terminals for use in systems controlling and monitoring electrical or electronic installations or equipment.
2. Description of the Prior Art
To switch circuits on and off and to indicate the voltage status, correct operation and faults, such installations require control and/or indicator units: pushbutton switches, pushbutton switches with integral indicator lamp, indicator lamps.
Patent EP-A-0 342 703 describes control or control and indicator units comprising a head and a block containing either the contacts or the luminous component, the two parts being separable or joined together. This design lends itself to a great variety of products.
Patent FR-A-2 616 265 describes one-piece pushbutton switches and patent FR-A-2 616 207 describes one-piece indicator lamps. The one-piece design enables direct fitting from the front to a panel or a wall. The screws connecting the conductors are not protected, however.
Document DE-A-83 32 474.7 describes a control or indicator unit including a cap protecting two screw terminals. Each terminal comprises a connection block in which is an opening through which the wire is passed. A screwthreaded hole opens into this opening and receives a clamping screw whose end clamps the wire, this end being in contact with the wire. The connection possibilities are limited by the diameter of the opening. Each terminal is screwed to a transverse partition with no space for a mobile plunger or for lamp power supply members attached to the terminals.
An object of the present invention is to provide monolithic or one-piece control and/or indicator units with protected screws. The arrangement of these units has advantages from the cost point of view and fitting and wiring are simple. A specific object of the invention is to provide switches with double-break contacts.